Proper window caulking

morwilwarinDecember 27, 2012

I've been having water leaks around all 12 of my replacement windows for months now. Windows have been re-wrapped and caulked, siding checked, and still, they leak. Today, someone said to see if the jamb is caulked/sealed to the window sill. I never heard of this, and there's no information about it online. However. I looked and sure enough, not on the window jambs are sealed where they meet the sill. Can anyone confirm if this is an accurate assumption that they need to be sealed?

Just for some background info, the original owner did the windows himself before we bought the house a year ago. All of the caulking had since cracked/warped/came of, so we assumed the new leaks were because of the use of poor quaulity caulking. Now, thousands of $ later and we still can't figure out the leak!

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Basically, seal the exterior perimeter of the replacement window, i.e where it meets the existing jambs or stops, etc. Also, make sure the weep holes (bottom of the window) are open (NOT caulked).

    Bookmark   December 27, 2012 at 9:47PM
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Sophie Wheeler

I'd suspect improper flashing. Caulk isn't the first line defense against water. Flashing is. A window that's properly flashed should be watertight even without caulk. Caulk is more for sealing against air penetration than water penetration.

    Bookmark   December 28, 2012 at 9:15PM
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Never caulk the side casings to the sill,it's the last place for the moisture to escape. Damming it up there is the primary cause of rotten sills and casings. Horizontal seams are never supposed to be caulked, if properly flashed or detailed to begin with they won't admit water. I agree completely with hollysprings that your problem elsewhere in the install.

    Bookmark   December 31, 2012 at 10:56AM
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That's a flashing issue, not a caulk issue.

    Bookmark   December 31, 2012 at 10:59PM
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Windows are sort of like skylites, and front loading washing machines. They are NOT water tight, they just shed the water correctly. You may actually be making the problem worse by improperly caulking, as it is probably not the answer. I agree with all previous posts relating to proper flashing. Anything else is a waste of $$.

    Bookmark   January 4, 2013 at 8:59PM
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